I can't think of who the dealers are for those, but I'd bet PRH will know.
I hope your block is tubed. If it isn't, it should be.
You ream the passenger side oil gallery to 5/8 and press in a brass tube. Then you peen over the tube where it breaks through into the lifter bore.
This stops all the leaks around the lifters. And that's a big deal.
You also need to increase the feed holes from that gallery down to the mains. I use 9/32 (.287) but some guys use 5/16. You do that to not only increase the size of the oil feed to the mains, you need to drill through that brass tube, otherwise you won't get any oil to the crank.
FWIW, I don't use a press fit on the tube. It's dumb. You should buy a reamer that is .0005-.0010 over MEASURED tube OD. Then you just slide the tube in by hand. Pressing the tube in is a PITA. Once you peen the tube it can never come out so it doesn't need press on it.
Then you use a set screw in the number one main to block the oil feed to the lifters, because you don't need any leaks on the drivers side lifter back either.
Or, you can drive a soft plug into the drivers side oil gallery in far enough that it goes past the feed hole coming up from the mains.